Question

Identify [X] used in the given reaction.
\[ [X] \xrightarrow{\text{Cu / 573 K}} [Y] \]
\[ [Y] \xrightarrow[(ii)\ H_2O/H^+]{(i)\ CH_3MgBr} \text{Tert.butyl alcohol (major product)} \]

• A. Propan-1-ol
• B. Butan-1-ol
• C. Propan-2-ol
• D. Butan-2-ol

Hint:

Secondary alcohols on heating with Cu give ketones, and ketones react with Grignard reagents to form tertiary alcohols.

Answer 1

The Correct Option is C

Step 1: Understand reaction with Cu at 573 K.
Alcohols on heating with copper at 573 K undergo dehydrogenation.
Primary alcohols give aldehydes, while secondary alcohols give ketones.
Thus, \( [X] \) must be an alcohol that gives a ketone \( [Y] \).

Step 2: Identify nature of [Y].
Since tertiary alcohol is formed after reaction with \( CH_3MgBr \), the compound \( [Y] \) must be a ketone.
Grignard reagent adds to ketones to give tertiary alcohols.

Step 3: Determine required ketone.
To obtain tert-butyl alcohol \( (CH_3)_3COH \), the ketone must be acetone \( (CH_3COCH_3) \).
\[ CH_3COCH_3 + CH_3MgBr \xrightarrow{H_2O/H^+} (CH_3)_3COH \]

Step 4: Identify alcohol [X].
The alcohol that gives acetone on dehydrogenation is propan-2-ol.
\[ CH_3CHOHCH_3 \xrightarrow{Cu, 573K} CH_3COCH_3 \]

Step 5: Conclusion.
Thus, the compound \( [X] \) is:
\[ \boxed{\text{Propan-2-ol}} \]